Pet food with visible particles and process for making same

ABSTRACT

The invention provides dry pet food diet compositions that include visible micronutrient particles comprising micronutrients, and improved methods for their preparation. The methods provide pet food diet compositions that have improved palatability and retention of micronutrients.

FIELD

The present invention relates to pet food compositions containingvisible micronutrient particles. The compositions have enhancedpalatability and nutrient visualization, and can be formulated to bedelayed-release, resulting in increased efficacy of nutrient delivery.

BACKGROUND

Fortification of pet food by the inclusion of micronutrients suchantioxidants, minerals, vitamins, carotenoids, glucosamine, chondroitinsulfate, nutraceutical ingredients and nutrient supplements is anefficient way to sustain and improve the health of companion animals.However, the conventional ways of incorporating micronutrients in drypet foods do not manifest any indication to either the pets or theirowners regarding the physical presence of the micronutrients. Thus, theonly indication that such nutrients are present is the label statementappearing on the package.

Pet foods containing separate nutrient-containing particles are known.However, physical segregation or selective consumption between differentkinds of kibbles may cause uneven intake of the fortified nutrients.Such externally incorporated nutrient bits are mixed among regular drypet food kibbles and may tend to segregate from the others upontransportation due to density and/or conformation differences, inaddition, some pets may have selective consumption of one kind ofkibble. Both situations may lead to inconsistent intakes of thefortified nutrients between the consumptions of food. Thus there is aneed for novel pet food compositions and for methods of theirmanufacture that overcome these problems. This invention is directed tothese, as well as other important ends.

SUMMARY

Unless otherwise indicated, the terms “%” or “percent” when used inconnection with an ingredient of the compositions of the invention isintended to refer to the percent by weight of the indicated ingredientin the composition.

In one aspect, the invention provides a pet food composition comprisinga plurality of kibbles, where the kibbles include one or moremicronutrient particles incorporated therein, which micronutrientparticles are visually distinct and comprise elevated concentrations ofone or more micronutrients, e.g. wherein the concentration of saidmicronutrient is higher in the micronutrient particles than in the restof the kibble, e.g., at least 10, 20 or 50 times higher.

In some embodiments, the micronutrient particles include one or moremicronutrients selected from antioxidants, minerals, vitamins,carotenoids, glucosamine, chondroitin sulfate, nutraceutical ingredientsand nutrient supplements.

In some embodiments of the pet food compositions of the invention, themicronutrient particles are delayed-release particles.

In some embodiments, the micronutrient particles are encapsulated.

In some embodiments of the pet food compositions of the invention, thekibbles contain the micronutrient particles in an amount of up to 10% byweight, or up to 5% by weight, or from 1% to 5% by weight, or from 1% to4% by weight, or 2% to 4% by weight of the pet food composition.

In some embodiments of the pet food compositions of the invention, themicronutrient particles are a different color than the kibbles, forexample.

The present invention also provides methods for producing kibbles thatinclude one or more micronutrient particles incorporated therein, whichmicronutrient particles are visually distinct and include one or moremicronutrients, which comprises the step of mixing micronutrientparticles which comprise one or more micronutrients together with anextrudate, and immediately extruding the mixture. In some suchembodiments, the extrudate is pre-conditioned prior to mixing with themicronutrient particles.

In some embodiments, the methods comprise the steps of:

-   -   a) providing a composition comprising pet food raw materials,        wherein the particle size of the raw materials is suitable for        extrusion;    -   b) preconditioning the pet food composition to produce an        extrudate;    -   c) mixing micronutrient particles which comprise one or more        micronutrients together with the extrudate; and    -   d) extruding the mixture.    -   In some embodiments, the extrusion of step d) is performed        immediately after the mixing according to step c).

In some embodiments, the mixing of the micronutrient particles with theextrudate is performed at a temperature lower than the temperature ofthe preconditioning.

In some embodiments of the methods of the invention, the micronutrientparticles are mixed with the extrudate by air-assisted injection.

DETAILED DESCRIPTION

It has been discovered in accordance with the present invention that petfoods compositions can be prepared that contain kibbles that haveincorporated therein visible micronutrient particles. In accordance withthe methods of the invention, the visually distinct micronutrientparticles (also referred to herein as “visible nutrient bits” or “VNBs”)are incorporated into the pet food kibble in a manner that bothpreserves the activity of nutrients in the micronutrient particles, andalso retains the color and shape integrity of the particle so they aredistinctly visualizable in the kibble.

The incorporation of visualizable micronutrient particles into thekibble provides several important advantages. For example, the pet owneris assured that the micronutrients are indeed present in the pet foodcomposition. In contrast to food compositions containing different kindsof kibbles, it is much more difficult for the incorporated particles tobecome physically segregated from the remainder of the kibble. Moreover,it is more difficult for the companion animal to selectively avoidconsuming the micronutrients in the micronutrient particles, and theinclusion of micronutrient, visualizable particles increases thepalatability of the food composition. The micronutrients can be providedat tightly controlled levels and distributed homogenously throughout thefood, and the interactions between micronutrients and other foodingredients are reduced.

Thus, in some embodiments, the present invention provides pet foodkibbles including one or more micronutrient particles incorporatedtherein, wherein the micronutrient particles are visually distinct andinclude one or more micronutrients.

A wide variety of micronutrients can be incorporated into the kibbles ofthe invention, including for example and not limitation, one or moreantioxidants, minerals, vitamins, carotenoids, nutraceutical ingredientsand nutrient supplements, for example glucosamine and/or chondroitinsulfate.

In some embodiments, the micronutrient particles may comprise amedicine. It is difficult to feed medicine to pet. Ideally, amaintenance diet containing wholesome nutrients will be suitable as thecarrier for the medicine delivery. Due to the quantitative precision ofthe VNB technology, the pet food kibbles can be formulated to include aprecise dosage of a drug. A kibble containing VNBs, wherein the VNBscomprise a drug, is a feasible and convenient way to deliver medicinefor pets on a quantitative manner.

In some embodiments of the pet food compositions of the invention, themicronutrient particles are delayed-release particles. Suchdelayed-release particles can be manufactured by, for example,processing protein rich ingredients such as corn gluten meal and yeastalong with the target nutrients and other components of themicronutrient particle. After processing, these micronutrient particlescan be digestively more slowly inside the animal's digestive system thantypical pet foods, thus extending the time of release of themicronutrient nutrients or other components.

In general, the kibbles of the pet food compositions of the inventioncan contain the VNBs in an amount of up to 10% by weight, or up to 5% byweight, or from 1% to 5% by weight, or from 1% to 4% by weight, or 2% to4% by weight of the pet food composition.

The VNBs of the pet food compositions of the invention are preferablyformulated to include one or more coloring agents, such that the VNBshave a color that is distinct from the kibble in which it isincorporated. Preferably, the color, specific shade or color, or both ofthe micronutrient particles are chosen such that the micronutrientparticles are distinctly visualized by both a companion animal and itsowner.

The incorporation of the VNBs into the pet food compositions of theinvention is accomplished in a manner such that the color and shapeintegrity of the particles is preserved through the extrusion process,resulting in incorporation of VNBs that are visible in the resultingkibbles. For example, in one embodiment, a typical pet food processingapparatus is employed having a live bottom holding bin into which theraw mix is fed. The raw mix is then transported via a variable speedfeeder screw to a preconditioner, where liquids including but notlimited to water, fat or oil, nutrients, additive, and steam are addedand the raw mix is preconditioned. After preconditioning, theconditioned mix (partially hydrated hot mix) is directed into theextruder barrel. In accordance with the methods of the invention, themicronutrient particles are added into the stream of hot mix immediatelyprior to the mix entering the extruder barrel. Adding the micronutrientparticles into the mix at a point after preconditioning is completeensures that the VNBs will not be subjected to the high temperatures andrelatively extreme conditions of the preconditioning, and also minimizesthe exposure to excessive hydration or mechanical stress, thuspreserving their physical integrity.

The VNBs can be added to the mix by any effective means. One preferredmethod of addition is by air-assisted injection, for example by using aside feeding device that allows for direct addition of an air streamcarrying VNBs into the mix. One such device employs a tube that has atone end (a) an inlet for compressed air configured to create an airstream in the tube, and a valve for regulating the flow thereof; at theother end (b) an injection nozzle that is inserted into the mix line ator near the head of the extrusion barrel; and (c) a hopper for holdingthe micronutrient particles is located in between (a) and (b), whereinthe particles are fed from the hopper into the air stream. In oneembodiment, the diameter of the inlet for compressed air stream isnarrowed from 10% to 60% before opening to the outlet pipe near thebottom of the hopper in order to create a very focused air streamapproximately perpendicular to the vertical axis of the hopper, whichdraws the particles out of the bottom of the hopper. The amount of VNBsfed into the extruder can be quantitatively controlled by, for example afeeder device such as those manufactures by Acrison, Inc., Moonachie,N.J. The VNBs can be dosed into the hopper of the side feeding device bythe feeder and then injected into the extruder via a stream ofcompressed air, thus reducing hydrothermal and mechanical stressesexerted on the VNBs and promoting their mixing into the stream.

Thus, the present invention also provides methods for producing kibblesthat include one or more micronutrient particles incorporated therein,which micronutrient particles are visually distinct and include one ormore micronutrients, which comprises the step of mixing micronutrientparticles which comprise one or more micronutrients together with anextrudate, and immediately extruding the mixture. In some suchembodiments, the extrudate is pre-conditioned prior to mixing with themicronutrient particles.

In some embodiments, the methods comprise the steps of a) providing acomposition comprising pet food raw materials, wherein the particle sizeof the raw materials is suitable for extrusion; b) preconditioning thepet food composition to produce an extrudate; c) mixing micronutrientparticles which comprise one or more micronutrients together with theextrudate; and d) immediately extruding the mixture.

As discussed above, raw pet food mix compositions are typicallysubjected to a preconditioning process that can include subjecting themix to humid conditions at elevated temperatures. Such preconditioningcan impair the nutritional value of many nutrients such as vitamins,carotenoids, antioxidants, etc. Addition of VNBs containing suchnutrients into the feed mix after preprocessing, and preferably as closeto the head of the extruder barrel as possible, protects the nutrientsin the VNBs from excessive exposure to thermal and hydrolyticconditions, and improves the retention of micronutrients.

The invention thus provides, in one embodiment, a pet food composition(Composition 1) comprising a plurality of kibbles, where the kibblesinclude one or more micronutrient particles incorporated therein, whichmicronutrient particles are visually distinct and include one or moremicronutrients, for example:

1.1. Composition 1, wherein the micronutrient particles include one ormore micronutrients selected from antioxidants, minerals, vitamins,carotenoids, glucosamine, chondroitin sulfate, nutraceutical ingredientsand nutrient supplements.

1.2. Any foregoing composition wherein the micronutrient particlesinclude one or more micronutrients selected from antioxidants, minerals,vitamins, carotenoids, glucosamine, chondroitin sulfite, nutraceuticalingredients, nutrient supplements and/or medicines.

1.3. Any foregoing composition wherein the micronutrient is a compoundwhich is labile under heat and/or moisture conditions normally occurringin manufacture of kibble.

1.4. Any foregoing composition wherein the micronutrient particlecomprises an extrudable binder, e.g., comprising gluten and/or rice.

1.5. Any foregoing composition wherein the micronutrient particlecomprises one or more micronutrients, one or more pigments, and anextrudable binder.

1.6. Any foregoing composition wherein the micronutrient particles aredelayed-release particles.

1.7. Any foregoing composition wherein the micronutrient particles areevenly distributed in the composition, e.g., wherein the coefficient ofvariance (CV) for distribution of a micronutrient provided in themicronutrient particles in the composition is less than 10%.

1.8. Any foregoing composition wherein the micronutrient particles areencapsulated.

1.9. Any foregoing composition wherein the composition is produced inaccordance with any of Method 1, et seq. below.

1.10. Any foregoing composition wherein the micronutrient particles haveapproximately the same density as the kibbles, e.g., wherein the ratioof the density of the kibble material to the density of themicroparticle is 2:1 to 1:2, e.g., about 1:1.

1.11. Any foregoing composition wherein the kibbles contain themicronutrient particles in an amount of from 1% to 10%, e.g., 2% to 5%by weight of the pet food composition.

1.12. Any foregoing composition wherein the micronutrient particles area different color than the kibbles, for example red.

1.13. Any foregoing composition wherein the micronutrient particles arefrom 0.5-10 mm in size, e.g. 1-4 mm in size.

1.14. Any foregoing composition where the micronutrient particlescomprise ascorbic acid and/or thiamine.

1.15. Any foregoing composition where the micronutrient particlescomprise rice and/or wheat gluten.

1.16. Any foregoing composition where the micronutrient particlescomprise flavoring and coloring.

1.17. Any foregoing composition wherein the micronutrient particlescomprise one or more orally acceptable pigments, e.g., iron oxide, in anamount effective to impart color to the micronutrient particle.

1.18. Any foregoing composition wherein the micronutrient particlecomprises a flavorant or palatability enhancer, e.g., bacon flavor.

1.19. Any foregoing composition where the micronutrient particlescomprise brewers rice, wheat gluten, ascorbic acid and thiamine.

1.20. Any foregoing composition wherein the micronutrient particles havesignificantly different composition from the rest of the kibble, e.g.,comprise at least 100 times the concentration of a particularmicronutrient.

1.21. Any foregoing composition where the micronutrient particlescomprise:

-   -   from 45% to 55% brewers rice;    -   from 35% to 45% wheat gluten;    -   from 1% to 5% ascorbic acid; and    -   from 1% to 5% thiamine hydrochloride.

In yet another embodiment, the invention provides a method (Method 1)for making kibbles for use in a pet food composition, wherein thekibbles include one or more micronutrient particles incorporatedtherein, which micronutrient particles are visually distinct and includeone or more micronutrients, e.g., a pet food composition according toany of Composition 1, et seq., supra, comprising the step of mixingmicronutrient particles which comprise one or more micronutrientstogether with an extrudate, and immediately extruding the mixture, forexample,

-   -   1.1. Method 1, wherein the extrudate is pre-conditioned prior to        mixing with the micronutrient particles.    -   1.2. Any foregoing method comprising the steps of:        -   a) providing a composition comprising pet food raw            materials, wherein the particle size of the raw materials is            suitable for extrusion;        -   b) preconditioning the pet food composition to produce an            extrudate;        -   c) mixing micronutrient particles which comprise one or more            micronutrients together with the extrudate; and        -   d) extruding the mixture.    -   1.3. The method of 1.2 wherein the mixture in step d) is        extruded immediately after mixing according to step c).    -   1.4. Any foregoing method wherein the mixing of the        micronutrient particles with the extrudate is performed at a        temperature lower than the temperature of the preconditioning.    -   1.5. Any foregoing method wherein the micronutrient particles        are mixed with the extrudate by air-assisted injection.    -   1.6. Any foregoing method wherein the micronutrient particles        are made by mixing ingredients comprising one or more        micronutrients, one or more pigments and an extrudable binder,        extruding the micronutrient mixture thus obtained, grinding the        micronutrient extrudate thus obtained to provide micronutrient        particles of the desired size, and drying the micronutrient        particles.

The following examples are further illustrative of the nature of thepresent invention, but it is understood that the invention is notlimited thereto. All amounts and proportions referred to herein and inthe appended claims are by weight, unless otherwise indicated.

Example 1—Preparation of Pet Food Containing Micronutrient Particles

One significant feature of the pet food compositions of the presentinvention is the visibility of the micronutrient nutrient-containingparticles in the pet food kibbles. Micronutrient particles were made ina different color than the typical food kibble, and incorporated intokibbles using the methods described herein, to minimize the thermal andhydrolytic processing of the mix containing the micronutrient particles.Pet food compositions were prepared incorporating either 2% or 4% of themicronutrient particles into a commercial canine adult dry formula.

Micronutrient particles were prepared having the following composition:

Component Percent by Weight Rice, Brewers 49 Wheat, Gluten 40 Ascorbicacid, usp, fine, granular 2.5 Thiamine hydrochloride 2.5 Sweet BaconFlavor 3 Red Iron Oxide Solution 3

The micronutrient particles were processed using a typical extrusionprocess for dry pet foods. After extrusion, the semi-dried kibbles werecollected from the extrusion line then ground coarsely. The resultingparticles were sieved and collected in between 1 mm and 4 mm screens,i.e., so that the particles were between 1 and 4 mm in size. Thecollected portion was dried using a hot air oven then stored underambient conditions until use. These micronutrient particles (dried colorbits) are herein referred to as “Visible Nutrient Bits” or “VNBs”.

The canine adult dry formulation was made with inclusion of either 2% or4% by weight of VNBs added to the feed line through a window in theconnection duct between the pre-conditioner and the extruder barrel,using an air assisted delivering devise as described above. The amountof VNBs fed into the extruder was quantitatively controlled by anAcrison feeder. VNBs were dosed into the hopper of the side feedingdevice by the Acrison feeder and then injected into the extruder via astream of compressed air.

The appearance of VNBs on the surface of dried kibbles of the canineadult dry formulation was examined visually. As expected, the non-VNBincluded Control did not show any apparent red bits on the kibblesurface, while the red VNBs appeared vividly on the surface of kibblescontaining either 2% or 4% of the VNBs. It was observed that the redVNBs appeared on every kibble of the 4% VNB included formula, but notnecessarily on the every kibble of the 2% VNB included formula. Fromthese results, it is believed that the inclusion of approximately 4% VNBis sufficient to result in visible VNBs on each kibble of the pet foodcomposition.

Example 2—Nutrient Distribution

Another important feature of the pet food compositions of the inventionis that the incorporation of micronutrient particles throughout thekibbles provides even distribution of fortified micronutrients amongindividual kibbles so that the companion animal (e.g., cat or dog) willhave even intake of micronutrients upon each occasion of foodconsumption regardless the amount of food intake. This is important, asthe differences in eating behavior among different pets (due to factorssuch as pet sizes, breeds, owner's feeding habits, and the tendency ofsome pets tend to eat small portions of their food throughout a day,while others consume all designated food during a single meal) canresult in under- or over-consumption of micronutrients for pets.

Pet foods containing separate nutrient-containing particles are known.However, physical segregation or selective consumption between differentkinds of kibbles may cause uneven intake of the fortified nutrients.Such externally incorporated nutrient bits are mixed among regular drypet food kibbles and may tend to segregate from the others upontransportation due to density difference. In addition, some pets mayhave selective consumption of one kind of kibble, and the owner may nottake a consistent quantity of the nutrient-containing particles from thepackage. These situations may lead to inconsistent intakes of thefortified nutrients between the consumptions of food.

In contrast, the pet food compositions of the present invention maintainthe visibility of included nutrient bits on kibble surface whileoffering the benefit of even rationing of the fortified micronutrientsfrom one bite to another regardless pet's eating behavior or owner'sfeeding habits.

The evenness of a micronutrient distribution in a pet food diet can beexpressed by the precision and accuracy of the nutrient incorporationamong sample duplicates.

The precision and accuracy of the methods of the invention fordistributing micronutrients were determined using manganese (Mn) as anindicator because Mn is usually fortified at small amounts in a diet,which increases the sensitivity of the nutrient distribution study. Acanine adult dry formula was prepared without (Control) and including of3% by weight of VNB. The diets were processed similar to those describedabove. Ten duplicates of either the non-fortified diet (Control) or 3%VNB included diet (Test) with a sample size of 400 gm for each duplicatewere collected randomly during production. Only the minimum amounts ofsample were used for Mn analysis in order to maintain the most sensitivedetection for the nutrient distribution; therefore, only 5 gm out ofeach 400 gm sample were used for Mn analysis, which was approximately 12kibbles per sample.

The evenness of the distribution of fortified micronutrient in a petfood diet can be expressed by the coefficient of variance (CV) ofcontents of the micronutrient among duplicates of samples. According toFDA guidelines, the maximum allowance for the CV for high potency drugamong duplicates of dosages is 10%. The Results are shown in Table 1:

TABLE 1 Mn content in canine adult dry food with or without theinclusion of 3% of VNB Mn (ppm; DMB) Control Test (0% (3% Sampleduplicate No. VNB) VNB) 1 19.4 34.7 2 22.7 41.0 3 19.2 34.4 4 19.6 35.65 20.6 38.2 6 20.7 38.5 7 19.4 34.8 8 21.0 41.0 9 18.3 33.9 10  22.141.1 Average 20.3 37.3 Std Deviation 1.38 2.96 Coefficient of Variance6.8%   7.9% Mn fortification target 0.0 14.7 Expected Mn content 20.335.0 Averaged recovery rate (%) — 106.61%

The dry VNBs contain 490 ppm of Mn on a dry matter basis. Therefore,inclusion of 3% of VNBs in a diet is expected to deliver 14.7 ppm of Mnin a diet, where the VNBs are evenly and accurately dispensed in anindividual kibble. It can be seen from the results in Table 1 that themethods of the invention can evenly and accurately dispend smallquantities of micronutrients among a pet food diet. As shown in Table 1,the Control diet contained an average of 20.3 ppm of Mn with a CV of6.8% among 10 duplicates of samples prior to the VNB inclusion, whilethe Test diet contained an average of 37.3 ppm of Mn with a CV of 7.9%after the inclusion of 3% of VNBs. Respecting the intrinsic CV of 6.8%for the Mn distribution in the Control diet, the VNB process only added1.1% of additional variability to the Test diet. Overall, according toFDA guideline, both conventional and the VNB methods for fortificationof micronutrients in a pet food diet can be recognized as precisemethods.

The accuracy of nutrient fortification is important to deliver efficacyof the fortified nutrient around the intended dosage level and can beexpressed by the ratio of the amounts of actually delivered nutrientversus the intended fortification level or the recovery rate. As the 3%of VNB delivers 14.7 ppm of Mn to the Test diet, the Mn level in thefinished Test diet is expected to be at 35.0 ppm. Respecting theaveraged Mn content in the Test Diet is 37.3 ppm, the averaged recoveryrate of Mn fortification among the Test diet is 106.6%, of which the6.6% above the target fortification level is not only well within FDA'smaximum tolerance (20%) for nutrient labeling but also is above theFDA's requirement for the minimum guaranty of the claimed fortification.

Thus, the results show that the methods of the invention are precise andaccurate methods for fortifying delicate amounts of micronutrients inpet food products.

Example 3—Nutrient Retention

As discussed above, the methods of the invention improve the retentionof fortified micronutrients in a diet through nutrient protection andreduced thermal processing. By incorporating the VNBs into a dietthrough a side feeding device such as the tubular device describedabove, the VNBs bypass approximately 1.5 to 4.5 min of hot and wetprocess conditions in the pre-conditioner, and are therefore heat labilenutrients such as vitamins, carotenoids, antioxidants, etc. are expectedto be shielded the from excessive exposure to thermal and hydrolyticconditions prior to extrusion so to improve the retention ofmicronutrients.

A nutrient retention study was carried out to compare the retention ofascorbic acid (vitamin C) in a dry kibble dog food formulationcontaining 2% or 4% of VNBs (Test diet) to that in a commercial dietfortified with vitamin C (Control diet). Vitamin C is one of the mostheat labile vitamins, and is sensitive to heat, hydrolytic, andoxidative degradation; and is therefore a good indicator for examiningthe effects of processing on nutrient retention.

The study was designed to fortify similar amounts of vitamin C in eitherthe Control or the VNB-included diets then compare the contents ofresidual vitamin C in between the finished foods. The Control diet wasmade from a commercial dry kibble formulation with fortification of1,000 ppm of vitamin C provided as a powder additive. For the Testdiets, vitamin C was fortified through inclusion of either 2% or 4% ofVNBs in the diet. The vitamin C retention rate was determined bycomparing the vitamin C content in the finished food after processing tothat in the ingredient mix prior to processing. The results are shownbelow in Table 2.

TABLE 2 The Vitamin C contents in the Control and 2 Test diets on a drymatter basis (DMB). Sample Control Test Sample Ingredient FinishedIngredient 100% 2% 4% Type Mix Food Mix VNB VNB*^(a) VNB*^(b) Vitamin C1242 711 98 7987 321 422 (ppm) DMB At 100% 271 443 Recovery % Vitamin C57.2 118.5 95.3 Retention Note: ^(a)The test diet contained 2% of VNBand 98% of Ingredient Mix. ^(b)The test diet contained 4% of VNB and 96%of Ingredient Mix.

As shown in Table 2, the vitamin C in the ingredient mix of the Controldiet was 1,242 ppm prior to the extrusion process and was 711 ppm in thefinished food after processing. Therefore, the vitamin C retention ratefor the Control diet was 57.2%. As the vitamin C content in VNBs was7,987 ppm, the theoretical content of vitamin C in the Test dietcontaining either 2% or 4% of VNB was expected to be 271 or 443 ppm,respectively with the inclusion of the 98 ppm of vitamin C from theingredient mix for the test diets. As the vitamin C content in finishedTest diet containing either 2% or 4% VNBs was 321 ppm or 422 ppm,respectively, the vitamin C retention rates were 118.5% for the 2% VNBsincluded diet and 95.3% for the 4% VNBs included diet, respectively. Theaveraged vitamin retention rate of the Test diets was 106.9%, which washigher than that of the Control diet (57.2%). While the measurement ofaverage retention values in excess of 100% for the Test sample suggestssome degree of experimental variability, the results support that theVNBs protect the Vitamin C from any substantial degradation duringprocessing. These results show that the methods of the invention improvethe retention of micronutrients through encapsulation and avoidance ofexcessive thermal and hydration processing.

Example 4—Palatability

Dogs prefer the food with inclusion of 4% of VNBs to the non-VNBincluded diet. A study was carried out to see whether inclusion of VNBsin a diet improves palatability. Canine adult dry food without or withthe inclusion of either 2% or 4% of VNBs was processed as thosementioned previously. For a preliminary study, either the 2% or 4% VNBsincluded diet was presented as the Test food to a dog taste panelconsisted of 25 dogs during a 2-day feeding session while the non-VNBincluded diet was presented as the Control food. The amounts of eitherthe Control or Test food consumed by each dog panelist during the 2-dayfeeding session were collected and analyzed. The preference was assignedto the food with the higher amounts of consumption between the two. Theintake ratio (IR) was determined by the ratio of the amounts of the Testfood consumption versus the overall consumption for each panelist. Theintake ratios were statistically analyzed using a Student T-test model.The palatability of food was expressed by the averaged intake ratio ofthe Test food along with the probability (p) value reported by theT-test. Win or loss is assigned to the Test food if its intake ratio issignificantly higher or lower than that of the Control based on a 95%confidence level according to the distribution pattern of single tailT-values; otherwise, the palatability of Test food is in parity with theControl food.

It was interestingly observed from the preliminary study that the dogpanelists preferred the Test food containing 4% of VNBs to the Controlfood at a ratio of 72 over 24 (or 3 to 1) with a significantly higher IRof 0.535 and a p value of 0.007 while the palatability of 2% VNBincluded diet was in parity with that of the Control food. To confirmsuch winning by the 4% VNB included diet, a confirmation study wasconducted using a 2-day by 50-dog taste panel to verify whetherdifferent dog panelists would make similar choices. Therefore, adifferent but up-sized taste panel comprised of 50 dog panelists wasused for the confirmation study. The very same foods were fed to the 50dog panelists for 2 days. The results confirmed the observations fromthe preliminary study that dogs preferred the 4% VNB included diet tothe non-VNB included control at a ratio of 69 over 29 (or 2.4 to 1) witha significantly higher IR of 0.581 at a p value of 0.01. The results ofboth studies are summarized in Table 3 below.

TABLE 3 Results of palatability tests Test Test Control No Protocol FoodFood Verdict Pref. IR 1 2-day by k9 Adult Canine Parity 40/52 0.467 25dogs 2% Bacon Adult p = 0.15 Bits Corn 2 K9 Adult Control Win 72/240.535 4% Bacon 0 p = 0.007 Bits inclusion 3 2-day by Win 69/29 0.581 50dogs p = 0.001

The results of the foregoing studies show that the methods of theinvention provide a new approach to fortify micronutrients in a dry petfood diet by the inclusion of visible and identifiable nutrient bits onthe surface or inside of dry pet food kibbles, which renders accurateand precise distributions of the designated doses of micronutrientsamong each handful of kibbles. The methods provide better retention formicronutrients than conventional methods because, inter alia, processingbypasses excessive exposure to hot and wet process conditions during theextrusion. In addition, the methods also provide dry pet foodcompositions having improved the palatability.

While the present invention has been described with reference toembodiments, it will be understood by those skilled in the art thatvarious modifications and variations may be made therein withoutdeparting from the scope of the present invention as defined by theappended claims.

We claim:
 1. A method for producing a plurality of kibbles, wherein eachkibble comprises one or more micronutrient particles incorporatedtherein for a pet food composition, wherein the micronutrient particlesare visually distinct and comprise one or more micronutrients and anextrudable binder, wherein the extrudable binder comprises rice andgluten, and wherein the method comprises: producing the micronutrientparticles, wherein producing the micronutrient particles comprises:mixing ingredients comprising the one or more micronutrients, one ormore pigments, and the extrudable binder to produce a micronutrientmixture; extruding the micronutrient mixture to prepare a micronutrientextrudate; grinding the micronutrient extrudate to provide the one ormore micronutrient particles of the desired size; and drying the one ormore micronutrient particles; preconditioning a composition comprisingpet food raw materials to prepare an extrudate; mixing the micronutrientparticles which comprise the one or more micronutrients together withthe extrudate to produce a mixture, extruding the mixture immediatelyafter mixing the micronutrient particles with the extrudate, andproducing a plurality of kibbles from the extruded mixture, wherein themicronutrient particles are mixed with the extrudate at a temperaturelower than the preconditioning temperature to retain one or morecharacteristics of the micronutrients of the micronutrient particles inthe extruded kibble, wherein the micronutrient particles comprise:brewers rice in an amount of from 45% to 55%; wheat gluten in an amountof from 35% to 45%; ascorbic acid in an amount of from 1% to 5%; andthiamine hydrochloride in an amount of from 1% to 5%, wherein theextruded kibbles have a coefficient of variance for the content of themicronutrient particles of less than 10%, and wherein the one or morecharacteristics of the micronutrient particles comprises one or more ofactivity of the micronutrients, color of the micronutrients, shape ofthe micronutrient, or combinations thereof.
 2. The method of claim 1,wherein the extrudate is pre-conditioned prior to mixing with themicronutrient particles.
 3. A method for producing a plurality ofkibbles, wherein each kibble comprises one or more micronutrientparticles incorporated therein for a pet food composition, wherein themicronutrient particles are visually distinct and comprise one or moremicronutrients and an extrudable binder, wherein the one or moremicronutrients comprise brewers rice, wheat gluten, ascorbic acid, andthiamin, and one or more of antioxidants, minerals, vitamins,carotenoids, glucosamine, chondroitin sulfate, nutraceuticalingredients, nutrient supplements, medicines, or combinations thereof,wherein the extrudable binder comprises rice and gluten, and wherein themethod comprises providing a composition comprising pet food rawmaterials, wherein the particle size of the pet food raw materials issuitable for extrusion; preconditioning the composition comprising thepet food raw materials to produce an extrudate; mixing the micronutrientparticles which comprise the one or more micronutrients together withthe extrudate to produce a mixture; immediately extruding the mixtureafter mixing the micronutrient particles with the extrudate, andproducing a plurality of kibbles from the extruded mixture, wherein themicronutrient particles are mixed with the extrudate at a temperaturelower than the preconditioning temperature to retain one or morecharacteristics of the micronutrients of the micronutrient particles inthe extruded kibble, wherein the one or more characteristics of themicronutrient particles comprises one or more of activity of themicronutrients, color of the micronutrients, shape of the micronutrient,or combinations thereof, and wherein the extruded kibbles have acoefficient of variance for the content of the micronutrient particlesof less than 10%.
 4. The method of claim 3, wherein the micronutrientparticles are mixed with the extrudate by air-assisted injection.
 5. Themethod of claim 3, further comprising producing the one or moremicronutrient particles, wherein producing the micronutrient particlescomprises: mixing ingredients comprising the one or more micronutrients,one or more pigments, and the extrudable binder to produce amicronutrient mixture, extruding the micronutrient mixture to prepare amicronutrient extrudate, grinding the micronutrient extrudate to providethe one or more micronutrient particles of the desired size, and dryingthe one or more micronutrient particles.
 6. The method of claim 5,wherein the micronutrient particles are 0.5-5 mm in size.
 7. The methodof claim 3, wherein the one or more micronutrients comprise medicines.8. The method of claim 3, wherein the micronutrient particles aredelayed-release particles.
 9. The method of claim 3, wherein themicronutrient particles comprise 1% to 10% by weight of the pet foodcomposition.
 10. The method of claim 3, wherein the micronutrientparticles further comprise one or more pigments.
 11. The method of claim3, wherein the micronutrient particles further comprise one or moreorally acceptable insoluble pigments in an amount effective to impartcolor to the micronutrient particle.
 12. The method of claim 3, whereinthe micronutrient particles comprise: brewers rice in an amount of from45% to 55%; wheat gluten in an amount of from 35% to 45%; ascorbic acidin an amount of from 1% to 5%; and thiamine hydrochloride in an amountof from 1% to 5%.
 13. The method of claim 3 wherein the micronutrientparticles comprise at least 100 times the concentration of a particularmicronutrient relative to the concentration of the particularmicronutrient in the rest of the kibble.
 14. The method of claim 3,wherein a ratio of the density of the kibble to the density of themicronutrient particles is 2:1 to 1:2.